This is a proposal for continuing support of the Center for Demography of Health and Aging at the University of Wisconsin-Madison, which was created in 1999 with a five-year P30 grant from NIA. The overall goal of the Center for Demography of Health and Aging remains to build a major research and training program in the demography of health and aging. The institutional architecture of CDHA is designed to create links between social demography and biomedical and epidemiological research on health and aging. Major themes of ongoing and developmental research activities within CDHA include (a) midlife development and aging; (b) economics of population aging; (c) inequalities in health and aging; (d) international, comparative studies of population aging; and (e) linking social-demographic and biomedical research in population aging. During its first five years, CDHA has grown from 39 to 54 faculty members; has successfully turned pilot projects into grants; has grown from about $3.3 million to $55 million in NIA support; has created unique data resources and a secure data enclave; and has substantially expanded training activities. CDHA coexists with the Center for Demography and Ecology and thus shares and extends a well-developed research infrastructure in administration, computing, print library, data library, and GIS facilities. CDHA's administrative core will provide leadership and administrative support for the Center. The program development core (9001) will support faculty, staff, and research assistants engaged in innovative pilot research projects that are likely to lead to major NIA support. The external innovative network core (9002) will continue a popular, networked current awareness service for research in the demography of aging and support regular workshops, conferences, and visits. The external research resources core (9003) will support user-friendly provision of large-scale public data resources in the demography of health and aging. The statistical data enclave core (9004) will operate and develop a facility for the analysis of sensitive data under secure conditions.